Corrosion Behavior Of Copper Current Collector For High Capacity Lithium Ion Batteries At Negative Electrode Potential

As a highly efficient secondary battery,lithium ion batteries have been widely used in a variety of portable electronic devices.However,with the expansion of its application to electric vehicles,aerospace,and large-scale energy storage,the storage performance,energy density and safety performance of battery have became one of the major research projects at home and abroad.The corrosion of the anode cUrrent collector of lithium ion battery afFects the storage performance and safety performance of the battery to a certain extent.In this dissertation,a simple and accurate calculation formula for calculating the specific surface area of foam metal is deduced.The corrosion behavior of copper foil and copper foam current collector under different potentials in the electrolyte environment of lithium ion battery during simulated battery operation is simulated.The results are as follows:(1)Atetrakaidecahedron mode with quadrangled-hexagon structure were built,in which the n,which is related to the regularity and geometric shape of porous materials,and K,which is connected to the itself and preparation method of materials,parameters of experimental subject were calculated by a formula via using measure parameters of the?(porosity)and d(pore size)of the metal foam simply and accurately.The specific surface area equation is established based on parameters,including n,K,porosity and pore size.It also takes into account factors,like material types and preparation process,introduces the material constant,and calculates the specific surface area of porous metal which is prepared by electrodeposited and high-pressure seepage casting methods.By comparing to experimental results of the specific surface area,it is found that theoretical results have smaller calculation error,verifying a highly applicable formula.(2)Under the corrosion environment at three electric potentials which contains-0.5V?-1.0V?-1.5V,respectively,each sample showed different degrees of corrosion,such as most corrosion pits,spherical corrosion products and cracks at-0.5V,and clusters generated at-1.0V,Among them,after the sample was corroded at-0.5V for 120h,the surface of sample was basically filled with corrosion pits,and even staggered corrosion cracks appeared in many regions.The corrosion surface of the copper foil at the potential of-1.0 V becomes larger,but the uniform corrosion surface increases,and no corrosion crack occurs.When the potential is-1.5V,a polygon-like corrosion product appears on the surface of the copper foil,and the overall corrosion is light.The copper foil substrate can be directly observed,and there is no corrosion crack.With the analysis of electrochemical impedance,it can be found that the corrosion degree of copper foil in a lithium ion battery electrolyte was decreased with the decline of experiment potential within the testing potential range.(3)By analyzing the corrosion micro-morphology of copper foam at different potentials in the electrolyte environment of lithium-ion battery,it can be found that the material may have both pitting corrosion and uniform corrosion in the electrolyte.The cross-effect of various factors cause diverse corrosion behavior of copper foam which is different from the copper foil at different potentials in the electrolyte.The corrosion degree of copper foam within the testing potential range was decreased and then increased with the decline of experimental potential,due to the diffusion effects,and the emerging of SEI membrane.